Potential, Resting

a potential difference between the contents of a cell or fiber and the extracellular fluid; the difference in potential is localized on the surface membrane. The membrane’s inner surface is charged electronegatively with respect to the outer surface.

Resting potential results from unequal concentrations of Na⁺, K⁺, and Cl^- ions on both sides of the cell membrane and from the membrane’s unequal permeability to these ions. In nerve and muscle cells, resting potential helps keep the membrane’s molecular structure ready for excitation in response to stimulation. All influences on a cell causing a prolonged and stable decrease in action potential result in decreased cell excitability or in total loss of the cell’s capacity to generate action potential. Such influences include metabolic disturbance, increase in extracellular content of K⁺ ions, and the effect of a strong electric current.